Antimicrobial Activity of Yerba Mate (Ilex paraguariensis) Aqueous Extracts against Escherichia coli O157:H7 and Staphylococcus aureus

Bioactive compounds from natural plant sources are becoming increasingly important to the food industry.Ilex paraguariensisis used in the preparation of a widely popular tea beverage (Yerba Mate) in the countries of Uruguay, Paraguay, Argentina, and Brazil. In this study, extracts of 4 brands of commercial tea, derived from the holly plant species,Ilex paraguariensis, were evaluated for their ability to inhibit or inactivate bacterial foodborne pathogens. The ultimate goal was to evaluate potential use of the extracts in commercial applications. Dialyzed aqueous extracts were screened for antimicrobial activity againstEscherichia coliO157:H7 andStaphylococcus aureus.S. aureuswas found to be the more sensitive to extracts thanE. coliO157:H7. Minimum bactericidal concentrations (MBCs) were determined to be approximately 150 to 800 μg/mL and 25 to 50 μg/mL againstE. coliO157:H7 andS. aureus, respectively. A Uruguayan brand had reduced activity againstE. coliO157:H7 compared to the Argentinean brands tested. It was concluded that Yerba Mate could be used as a potential antimicrobial in foods and beverages against these pathogenic bacteria.